Flash dry wood filler



Patented Sept. 25, 1951 a UNITED STATES PATENT OFFICE nLAsHnnY WOOD FILLER WaltenK. Mofitt, Flint, Mich, and Christopher J 'Welz, Westficld, N. J., assignors to E. I. du

:Pont. de Nemours. & Company, Wilmington, DcL, a-conporation of Delaware Y No Drawing;

. 1 This invention relates to a wood filler composition exhibiting unusually fast drying properties and more particularly to a fast drying, wood filler composition which dries quickly, is economical,

and is adapted to conveyerized production line or lighter, the finish may have a muddy appearance and gray looking pores. The primary function of a filler is to fill the'grain to render a smooth foundation for the topco'at's. 'fi-ll'e rs are fundamentally inert, colorless, substantially transparent pigments with the desired amounts of prime color pigments, to accomplish specific color efiects, dispersed in a liquid vehicle consisting of non-volatile binding materials ina suitable thinner. In some instances a high pi portion of prime color pigments is usedin order that the product function both as afillerand a stain; However, in general, the Wood is first stained preferably with a non-.grai-n r-aising stain; wash-coated and then filled. The filler is followed by a sealer and topcoats. Fillers range in consistency from thick pastes to thin sprayable liquids for application by hand brushing, dipping or spraying. Trends are toward production line, conveyorized wood finishing where the multiple operations of finishin are accomplished in a minimum period of time with a minimum of labor. v After applying the filler by either of the methods, it is allowed to set for a. short period of time to approach a better working consistency by loss of volatile constituents. Thereafter, the filler is wiped into the grain of the wood with coarse cloth, such as burlap, or excelsior across the grain followed by light wiping with the grain to remove the excess filler without disturbing that deposited in the pores.

Many fillers require a twelve-hour or longer air-dry period before proceeding with the sealer and topcoats. Production line operations of wood finishing are unable to tolerate such lengthy drying periods and, consequently, faster drying fillers which may be 'force dried for a period as little as one hour at a temperature'in the range of 100 to 140 F. were developed. More recently, filler improvements have led to the 'elimina'tionoi force Application December 31, 1941, Serial No. 795,152

5 Claims. (01. 260-22) drying and to the application of sealers with virtually no delay for filler drying. The filler composition of this invention concerns this latter improved type of filler.

: The composition and the concentration of the binder in the filler play an important role in controlling the application characteristics of the filler. It is essential that the binder is not attacked by the solvents of the sealer or the topcoats. Drying and semi-drying oils as binders are undesirable because they lead to swelling by solvent action of subsequent finishing coats known as filler puffing with retarded drying and reduced scratch resistance as a result of the swelling action. It is easily understood that a significant reduction in the content of offending binder accomplishes a change in this objectionable characteristic of the fillers.

This invention has an object the provision of a wood filler composition the use of which accomplishes speed-up of finishing operations as a result of its flash-dry properties. Another object is the provision of a filler composition low in nonvolatile binder to eliminate filler puifing. A still further object of this invention is provision of an economical method of wood finishing which does not induce sacrifice in the quality and beauty of the finished wood as accomplished by the slower orthodox methods of Wood filling. The invention further provides a system of wood filling wherein a substantially binderless wood filler is sandwiched between a wash coat and filler-followup coat, the undercoat and :topcoat functioning as an adhesive binder for the pigment of the filler in addition to their normal functions. This invention has a still further object of providing economy in wood finishing by elimination of the orthodox grinding of the pigment in the binder in addition to economy resulting from speedup finishing schedules.

These objects are accomplished by mixing a high concentration of inert and prime color pigments in a liquid vehicle comprising a volatile high solvency hydrocarbon solvent boiling between C. and 215 C. containing at least 25% aromatic hydrocarbons, a compatible bodying agent which may be either non-volatile or volatile plus, preferably, a surface active agent adequate for pigment wetting under adverse conditions associated with the use of the product. The inert pigment is called an extender pigment in the examples and in addition to being inert, is characterized by low opacity, low hiding power or substantial transparency in an oleoresinous vehi'cle. The defractive index of the extender pig-- m'entshould fall within the range of 1.45 and 1.70.

- varnishes, Lacquers, and Colors.

The oil absorption of the pigment may be meas absorption of about 25. The binder is present in.

amount less than 6 parts for each 100 parts of total pigment. This pasty mass of wetted pigment,

a sealer or a top coat whereby binder is supplied to the pigment sandwiched in between.

Although the liquid vehicle wetting the pigment in the wood filler may contain non-volatile material which normally may be considered a binder, the concentration of non-volatile material in the vehicle in the proportion to the pigment is insufficient to produce significant binding action on the pigment to "form a coherent pigmented mass on loss of the volatile constituents. Therefore, the compositions of this invention containing six parts or less of binder for each 100 parts of pigment are defined as binderless wood fillers. Orthodox 'fillers generally contain at least twice as-much non-volatile binder. as do products of the present invention.

The following examples are given by way of iilustration as binderless wood fillers representative of this invention. Other modifications will readily occur to those skilled in the art.

EXAMPLE I WALNUT FILLER First portion 7 Per cent Linseed oil alkyl resin (67% oil length) 2.0 Raw linseed oil Turkey burnt umber 4.1 High solvency petroleum hydrocarbon (B.'P. 170-215 0.) 3.0 High solvency petroleum hydrocarbon (B. P. 130-190 C.) 19.6

Wetting agent 0.2

Water 0.7

Second portion Extender pigment 69.51

Per cent Linseed oil alkyl resin (67% oil length) 2.0 Raw linseed oil 1.0 Wetting agent 0.2 Turkey burnt umber 4.1 Extender pigment 69.4

Total solids ,1 76.7,

recognized as a wood filler, is utilized by application over a wash coat and is followed by either- The non-volatile binder is present in the proportion of 4.3 parts for each parts of pigment or at a ratio of 1 to 23.

The wetting agent used in this example was sorbitan trioleate which is a neutral, heat stable, non-volatile, oily liquid surface active agent. oil soluble, but dispersible in water. However, any other water dispersible, water insoluble characteristically similar non-ionic wetting agent would serve satisfactorily.

The linseed oil alkyd resin used in this example was a glyceryl phthalate resin modified to the extent of 67% oil length, by weight, said resin having an acid number in the range of 2.5-5.5 and a viscosity in the range of 10-18 .poises at 25 C.

I I .The high solvency petroleum hydrocarbons contain substantial amounts of aromatic hydrocarbons and are characterized by an aniline point of 4 C. in the case of thefraction distilling within the range of PTO-215 C. "(Unionsolvent #40 or Amsco Solv D) and an aniline point of -.-8 C. for the material distilling within the range of -190 C. (Union Solvent-#30 or-Amsco B).

EXAMPLE n NATURAL FILLER First portion Per cent Linseed oil alkyd resin (67% oil length) 2.0 Raw linseed oilv 1.0

High solvency petroleum hydrocarbon (B. P. -215 c.)' 3.0' High solvency petroleum hydrocarbon (B. P. 130190 C.) 19.1

Wetting agent 0.2

,Water 0.7

Second portion Extender pigment 74.0

The first portion containing no prime color pigment was mixed for five minutes and then,

as a second portion, the extender pigmentwas added and mixing continued for thirty minutes.

This natural color' filler contained the following solids:

Per cent Linseed oil alkyd resin (67% oil length) 2.0 Raw linseed oil 1.0 Wetting agent 0.2 Extender pigment 74.0

Total solids L 17.2

The wetting agent and extender pigment used in this example are the same as in Example I. The non-volatile binder is present in the proportion of 4.3 parts for each 100 parts of pigment or at a ratio of 1 to 23, the same as in Example I.

The following example illustrates a mohogany color flash dry filler with an anti-settling agent and no surface active agent.

EXAMPLE III MAHOGANY FILLER First portion Per cent Linseed oil alkyd resin (67% oil length) 2.0 Raw linseed oil 1.0 Aluminum stearate 1.2

High solvency petroleum hydrocarbon (B. P. ITS-215 C.) High solvency petroleum hydrocarbon 3' F? E-PFIT- Second portion 7 Val; iDyke brown pigment o v 1 Third portion solvency petroleum hydrocarbon (B,P. 130-190" C.) :3;0 Extender pigment 1 61.0

ibbfo The components of the first portion were charged in a pony .paint mixer and mixed for five minutes; then, as a second portion, .ithe prime color pigment was gradually added .and mixed one hour and finally, as athird portion, the hydrocarbon and extender pigment were added and mixing was .continued for additional minutes. During the mixing .of the first portion and after the addition of the second portion sufficient heat is evolved to cause the aluminum stearate to dissolve in the hydrocarbon. On cooling the aluminum stearate develops agel structure which functions as a retardant for pigment settling. In this product the non-volatile binder is present in the ,ratio of 1 part of binder to parts of pigment, wherein the aluminum stearate is considered part of the pi g.- mentation.

The following example is representative of a flash dry filler for use in producing color contrast wherein the grain is filled with the mate- ;rial lighter in color than the wood.

WHITE FLASH DRY FILLER First portion Per cent Linseed oil alkyd resin (67% oil length) 2.0 Wetting agent 0.2 Raw linseed oil 1.1 High solvency petroleum hydrocarbon.

(B. P. 175-215 C.) 3.3

Second portion Low reactivity zinc oxide 13.6

Third portion High solvency petroleum hydrocarbon (B. P. 130-190 (3.) 15.7 Water 0.9

Fourth portion Extender pigment 63.2

As in the previous examples, the first portion was mixed five minutes and after addition of the color pigment mixing was continued for an hour before let-down with the third portion and finally mixed for 15 minutes after addition of the extender pigment. All additions were slowly and gradually made in order to avoid nonuniformity.

Highly pigmented products frequently create a problem as a result of the pigment settling to a hard cake which is difficult to redisperse after extended storage. Foregoing Example III illustrates the use of aluminum stearate gel structure functioning as an anti-settling agent. *The following example illustrates the successful use of a small amount of oil in water emulsion wherein the internal phase comprises raw linseed oil and linseed oil acids.

EXAMPLE V NA'TURAL FLASH Dex FILLER First portion Percent Linseed oil alkyd resin (67% 0'11 length) 2.0 ,Raw linseed oil 1;0

After the extender pigment was added and mixed in the manner heretofore described, the emulsifled linseed oil was added and mixing was continued for five minutes. "The emulsion with the water as the external phase had the following composition:

Percent Water 81.9 Raw linseed oil 16.2 Lin-seed oil acids 0.5 Sodium bicarbonate 0.3 iBorax 0.3 Sodium silicate 0.8

Like the other examples, this filler contains nonvolatile binder in the ratio of 1 part to 23 parts of pigment.

A variety of materials functioning as bodying agents may be used as anti-settling agents. How ever, for economy in order that fillers may be formulated and reduced with petroleum hydrocarbons as the volatile constituents, these agents must function in the presence of petroleum hydrocarbon and not be precipitated thereby. Water was also observed to function as an antisettling agent.

Thefollowing example represents a binder to pigment ratio of about 6 parts of binder to 100 parts of pigment or 1 part of binder to about 16 parts of pigment, which is the practical upper limit of binder in the filler compositions classified as flash dry. Fillers with still high binder ratios may be employed in the method of wood filling disclosed in this invention, but the drying time of the filler prior to application of the follow-coats is extended progressively to several "hours and longer. The flash dry fillers permit application of the follow-up coats in less than one 'hour and preferably less than 30 minutes without filler pufling. Examples I to V represent fillers which permit application of .topcoats in about 15 minutes with satisfactory results. This Example VI yielded satisfactory results when topcoated in 30 minutes with no significant difference detected between this finish and that resulting from topcoating after one hour of filler drying.

between the wash coat and 'ing oil modified alkyd 7 EXAMPLE VI WALNUT FILLER First portion Per cent Linseed oil alkyd resin (67 oil length) 3.7 Raw linseed oil 0.5 Turkey burnt umber 4.0

High solvency petroleum hydrocarbon High solvency petroleum hydrocarbon (B. P. 130-190 C.) 18.8 Wetting agent 0.2 Water 0.8

- Second portion Extender pigment 69.0

Mixing was conducted as in Example I.

In compositons containing the higher ratios 01 binder which is predominantly an oxidizable oil, it is preferred to include a small percentage of an orthodox drier, preferably lead and manganese, to produce thorough drying. However, the presence of a metallic drier is not essential to the use of the flash dry fillers.

Although it is generally preferred to use a filler having a binder ratio within the limits disclosed in the foregoing examples, a satisfactory filler may contain even less non-volatile binder as shown in the following example wherein a volatile higher alcohol such as octyl alcohol functions as a temporary binder.

EXAMPLE VII WALNUT FILLER This filler contains non-volatile binder in the ratio of 1 part to '73 parts of pigment. The sole non-volatile binder in this example is raw linseed oil, the primary function of which is to wet the pigment with a primer coat to facilitate further wetting in the process of sandwiching the filler sealing coat. Although this composition found successful utility as a wood filler, the unusual odor contributed by the octyl alcohol may be objectionable. Consequently preferred compositions are those which do not require an operator to acclimate himself to new and different odor characteristics. It was discovered that a filler in which the octyl alcohol was directly replaced with petroleum hydrocarbon failed to yeld equivalent quality to that of the filler containing of octyl alcohol. It was further discovered that the satisfactory functioning of the alcohol was not related to the presence of the alcoholic hydroxyl, but apparently was related, in some manner not understood, to the viscosity of this constituent. This contention was based on the observation that a solution of dryresin in petroleum hydrocarbon having the same viscosity as that of. octyl 8 alcohol yields equivalent results when substituted in thefiller. The mixture of 2 parts of the described linseed oil alkyd solvency petroleum hydrocarbon (B. P. 175- 215 C.) exhibits the same viscosity as that of octyl alcohol, which is reported in the International Critical Tables as 7.2 centipoises and at 25 C. and 8.9 centipoises at 20 C., expressed in absolute units. Viscosity measurements in practice were made by the A. S. T. M. D-333-40 method using a Du Pont No. '7 cup which is equivalent to the A. S. T. M.'No. 1 consistency cup having an orifice diameter of 0.07 inch. Under these conditions the viscosity of N-octyl alcohol is 26 seconds :1 second at 25 C.

In the above examples the mixing was done in a relatively high speed paddle mixer such as a pony paint mixer, but it has also been found that a heavy duty slow speed mixer such .as a W 8: P or other mixer which subjects the mass to a kneading action produces a product of exceptionally high quality. The following exampleillustrates this embodiment of the invention:

EXAMPLE VIII Per cent China-wood/linseed oil alkyd resin (67% oil length) 2.51 Raw linseed oil 0.63

High solvency petroleum hydrocarbon High solvency petroleum hydrocarbon (-190" C.) 16.30 Wetting agent 0.20 Water 0.85 Raw Italian siennalight 1.10 Turkey burnt umber 0.67 Burnt sienna 0.34 Extender pigment 74.20

All the ingredients are loaded into a W '& P mixer provided with cooling water circulating through its jacket and ground for about one hour. The product is then ready for packaging;

In place of the film-forming ingredients used to illustrate the invention in the above examples, a large variety of other film-forming agents may be used to replace them in equivalent amount. In addition to the linseed oil alkyd resin disclosed in the examples, other medium and long oil length drying oil modified alkyd resins may be substituted. Unmodified soft maleic type resins may be used. varnishes based on dehydrated castor oil with either ester gum alone of in combination with the pentaerythritol esters of rosin are also useful. Asphaltic varnishes based on gilsonite alone, in combination with limed rosin, or incombination with drying oils may also be used. The use of gilsonite varnishes,.however, is limited to the darker colored Wood fillers.

It is also possible to prepare a putty having no film-forming binder Whatever as shown in the following example:

EXAMPLE IX Per cent Micronized talc 11.7 Amorphous silica, 46.5 Turkey burnt umber 5.8 Octyl alcohol 5.8 Gas carbon black 1.1

High solvency petroleum naphtha (B. P.

resin and 3 parts of high Thei-ngredients are mixed as shown in'Exdiately although those having about 6 :parts binder will require about 15-39 minutes to dry sufficiently to accepta-top coat In the preferred embodiment of this invention, 100 parts of filler contains not less than parts and not more than 15 parts of liquid material having a viscosity'not less than 7 centipoises at 2 5 C said liquid being compatible with the petroleum hydrocarbon of thefille'r vehicle and not precipitated by V. M. 8; P. naphtha which is generally used for reduction of the filler to application consistency with the non-volatile binder being present at a ratio between 1 part to 16 parts of pigment and lpart to '75 parts of pigment. Many examples of modified fillers will occur to those skilled in the art by using other extender pigments such as silica, silex, asbestine or china clay. Any of these and similar inert inorganic pigment extenders having the refractive index, low opacity, low hiding power and low oil absorption may be used in the examples.

The prime color pigments generally used in orthodox wood filler may be used in the flash dry filler of this invention. Color pastes of pigments predispersed in oil, resin or volatile liquid may be used to introduce the color provided the amount of non-volatile binder added thereby does not cause the total non-volatile binder to alter the ratio of binder to pigment to a value outside the specified limits. These color pastes are preferably added in the first or second portion during the manufacture of the filler. The ratio of extender to prime pigment is rather critical and there should be at least 4 parts of extender pigment to each part of prime pigment. The former is usually transparent or translucent with poor hiding power; whereas the latter is usually a color and in any event has a high hiding power and high oil absorption.

Sorbitan trioleate is the preferred surface active agent or wetting agent. However, other oil or organic soluble non-ionic wetting agents which show virtually no solubility in water may be used. As examples are the long chain fatty acid partial esters of hexitol anhydrides, linseed oil fatty acids, and liquid esters of phthalic anhydride and aliphatic alcohols, such as dibutyl phthalate.

Volatile constituents of the filler are, for economical reasons, preferably high solvency petroleum hydrocarbons although toluene and xylene or aromatic hydrocarbons boiling above 100 C. to 215 C. may be used. Use of highly aliphatic hydrocarbons is avoided because they may cause precipitation of certain potential non-volatile binders. Mixtures of lacquer solvents and diluents may be used, but high cost rules them out since they offer no advantage over the high solvency petroleum hydrocarbons. In such mixtures it is desirable to avoid highly active solvency in order that the wash coat is not attacked by the filler and its effectiveness partially destroyed.

In the preferred application of the filler, it was preceded by a wash coat and followed by a sealer. The coating compositions comprising polyvinyl butylraldehyde resin, cellulose nitrate and shellac as described in U. S. Patent 2,293,558 are particularly useful as a wash coat and are preferred. However, a conventional furniture lacquer sealer or top coat may be used as a washcoat. One Wet coat of wash primer was applied by spraying at 10% solids, preferably in the range of 8-l2% solids. Sol id s lower than 8% do not yield the optimum quality from the standpoint of color and clarity. For spray application of the filler, the material was reduced with an equal volume of petroleum hydrocarbon thinner such as V. M. & P. naptha. Reduction was less for brush application.. Excess filler was removed by wiping and the filled finish was coated with a sealer applied by spraying at 12% solids or at the normal solids at spraying consistency. A coat of the composition preferred as the wash, coat primer may be used equally as well; forthe coat following the 1111;; The coating subsequent to the filler is not limited to sealers'or primers, regular topcoat 'corfr'positiohsrriay also be used. The liquid vehicle of the sealer or its equivalent wets the filler, the'fwetting properties of which are enhanced by the surface agent andthe non-volatile oif-birider; and penetrates through the filler to attack and partially soften the wash coat. This action causes the wash coat to function as an adhesive in addition to its normal functioning and, thereby, the filler is adhesively sandwiched and anchored in the finishing system.

The binderless filler of this invention adhesively anchored in the furniture finish yields satisfactory quality in regard to such properties as scratch resistance, clarity, color contrast and cleanup in this economically accelerated process of filler application. By scratch resistance is not meant the resistance to surface scratching and marring which is a functional property of the topcoat. Rather, it means the resistance of the finish to shearing or flaking at the filler interfaces when subjected to severe scratching with the edge of a coin or similar object. The built up finishes including these binderless fillers exhibit greater freedom from filler puffing than is observed with orthodox fillers. The use of these fillers speeds up wood finishing operations as a result of its flash dry characteristics which depend on volatile loss of vehicle rather than on drying or polymerization properties of the nonvolatile binder characteristic of orthodox fillers. The use of these fillers renders wood finishing more adaptable to conveyorized methods of production line operations and consequential economy. Economy in, labor costs is more significant than economy of material since the use of the filler requires the preliminary wash coat which is not universally used in wood finishing. The

'follow-up coat after the filler is not considered as an additional coat since it may be a regular topcoat if a sealer is not in normal use. The higher quality finishes involving orthodox fillers normally include both the wash coat and the sealer. Economy is also accomplished by simplicity of the manufacture of the filler which dispenses with orthodox pigment grinding, but which provides for the use of prime color pigment pastes if the pastes are more conveniently available than the dry color pigments.

It is apparent that many widely difierent embodiments of this invention may be made without departing from the spirit and scope thereof, and therefore, it is not intended to be limited except as indicated in the appended claims.

We claim:

1. A filler which has approximately the following composition:

. I Per cent Linseed oil alkyd resin (67% oil length) 1 2.0 Raw linseed oil 1.0 Color pigment 4.1

High solvency petroleum hydrocarbon (B. P. 170-215 C.) 3.0

High solvency petroleum hydrocarbon (B. P. 130-190" C.) 19.6 Wetting agent 0.2 Water 0.7 Extender pigment 69.4

12 said binder being dispersed in a liquid petroleum hydrocarbon vehicle, the said vehicle containing the binder having a viscosity of at least 7 centipoises at 25 C. and being present in amount between -and 15 parts per 100 parts of total wood filler.

4. The product of claim 3 in which the ratio of binder to pigment is one part of binder to about 23 parts of pigment.

5. The product of claim 3 in which the extender pigment is hydrous calcium sulfate.

WALTER K. MOFFETT. CHRISTOPHER J. WELZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,011,041 De Phillips Aug. 13, 1935 2,225,262 Dietz et a1 Dec. 17, 1940 

3. A WOOD FILLER WHICH DRIES SUFFICIENT TO ACCEPT SURFACE COATES WITHIN ABOUT ONE HALF HOUR COMPRISING FROM 16 TO 75 PARTS OF TOTAL PIGMENT CONSISTING IN MAJOR PROPORTION OF AN INERT EXTENDER HAVING A LOW OIL ABSORPTION AN ONE PART OF BINDER SELECTED FROM THE GROUP CONSISTING OF VEGETABLE DRYING OILS AND VEGETABLE DRYING OIL MODIFIED ALKYD RESINS AND MIXTURES THEREOF, THE SAID BINDER BEING DISPERSED IN A LIQUID PETROLEUM HYDROCARBON VEHICLE, THE SAID VEHICLE CONTAINING THE BINDER HAVING A VISCOSITY OF AT LEAST 7 CENTIPOISES AT 25* C. AND BEING PRESENT IN AMOUNT BETWEEN 5 AND 15 PARTS PER 100 PARTS OF TOTAL WOOD FILLER. 